feat: reference past chats with @-mentions

.changeset/session-mentions.md

@@ -0,0 +1,6 @@
+---
+"kilo-code": minor
+"@kilocode/cli": minor
+---
+
+Reference past chats inline with `@` in the prompt. Typing `@` now surfaces a "Past chats" option that opens a searchable picker of previous sessions (scoped to the current workspace/worktree, searched like the Agent Manager session search); selecting one attaches that session's transcript as context so the model can build on a prior conversation. Clicking the mention opens that session. Available in the CLI TUI and the VS Code extension.

packages/kilo-ui/src/components/message-part.tsx

@@ -950,9 +950,23 @@ function HighlightedText(props: { text: string; references: FilePart[]; agents:
 
   const data = useData()
 
+  const session = (segment: HighlightSegment) => {
+    const ref = props.references.find((ref) => ref.source?.text?.value === segment.text)
+    const url = (ref as { url?: unknown } | undefined)?.url
+    if (typeof url !== "string" || !url.startsWith("session:")) return
+    return url.slice("session:".length)
+  }
+
   const click = (segment: HighlightSegment, e: MouseEvent) => {
-    if (segment.type !== "file" || !data.openFile) return
+    if (segment.type !== "file") return
     e.preventDefault()
+    // Past-chat mentions carry a session: URL — open that session instead of a file.
+    const id = session(segment)
+    if (id) {
+      data.navigateToSession?.(id)
+      return
+    }
+    if (!data.openFile) return
     const path = segment.text.replace(/^@/, "")
     if (path) data.openFile(path)
   }
@@ -962,7 +976,9 @@ function HighlightedText(props: { text: string; references: FilePart[]; agents:
       {(segment) => (
         <span
           data-highlight={segment.type}
-          data-clickable={segment.type === "file" && data.openFile ? "" : undefined}
+          data-clickable={
+            segment.type === "file" && (session(segment) ? data.navigateToSession : data.openFile) ? "" : undefined
+          }
           onClick={[click, segment]}
         >
           {segment.text}

packages/kilo-vscode/src/KiloProvider.ts

@@ -63,6 +63,7 @@ import { handleSidebarWorktreeMessage } from "./kilo-provider/sidebar-worktree"
 import { parseMessageFiles, type MessageFile } from "./kilo-provider/message-files"
 import { renameSession } from "./kilo-provider/rename-session"
 import { handleFileSearch } from "./kilo-provider/file-search"
+import { handleSessionSearch } from "./kilo-provider/session-search"
 import { handleFilePicker } from "./kilo-provider/file-picker"
 import { watchFontSizeConfig } from "./kilo-provider/font-size"
 import { getTerminalContents } from "./services/terminal/context"
@@ -289,6 +290,12 @@ export function unwrapSyncEvent(event: SSEPayload | RawSyncPayload): ProviderEve
   }
 }
 
+type ContextRequestMessage =
+  | { type: "requestFileSearch"; query: string; requestId: string; sessionID?: string }
+  | { type: "requestSessionSearch"; requestId: string; sessionID?: string }
+  | { type: "requestFilePicker"; requestId: string }
+  | { type: "requestTerminalContext"; requestId: string; sessionID?: string }
+
 export class KiloProvider implements vscode.WebviewViewProvider, TelemetryPropertiesProvider {
   public static readonly viewType = "kilo-code.SidebarProvider"
   private readonly instanceId = crypto.randomUUID()
@@ -1298,21 +1305,10 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
           break
         }
         case "requestFileSearch":
-          await handleFileSearch({
-            client: this.client,
-            message,
-            current: this.currentSession?.id,
-            context: this.contextSessionID,
-            dir: (id) => this.getWorkspaceDirectory(id),
-            open: (dir) => this.getOpenTabPaths(dir),
-            post: (msg) => this.postMessage(msg),
-          })
-          break
+        case "requestSessionSearch":
         case "requestFilePicker":
-          await handleFilePicker({ requestId: message.requestId, post: (msg) => this.postMessage(msg) })
-          break
         case "requestTerminalContext":
-          void this.handleTerminalContext(message.requestId)
+          await this.handleContextRequest(message)
           break
         case "chatCompletionAccepted":
           this.chatAutocomplete?.telemetry.captureAcceptSuggestion(message.suggestionLength)
@@ -2041,6 +2037,40 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
     this.pendingSessionRefresh = ctx.pendingSessionRefresh
   }
 
+  private async handleContextRequest(message: ContextRequestMessage): Promise<void> {
+    if (message.type === "requestFileSearch") {
+      await handleFileSearch({
+        client: this.client,
+        message,
+        current: this.currentSession?.id,
+        context: this.contextSessionID,
+        dir: (id) => this.getWorkspaceDirectory(id),
+        open: (dir) => this.getOpenTabPaths(dir),
+        post: (msg) => this.postMessage(msg),
+      })
+      return
+    }
+    if (message.type === "requestSessionSearch") {
+      await handleSessionSearch({
+        client: this.client,
+        message,
+        current: this.currentSession?.id,
+        context: this.contextSessionID,
+        dir: (id) => this.getWorkspaceDirectory(id),
+        exclude: this.currentSession?.id,
+        post: (msg) => this.postMessage(msg),
+      })
+      return
+    }
+    if (message.type === "requestFilePicker") {
+      await handleFilePicker({ requestId: message.requestId, post: (msg) => this.postMessage(msg) })
+      return
+    }
+    if (message.type === "requestTerminalContext") {
+      void this.handleTerminalContext(message.requestId)
+    }
+  }
+
   private async handleTerminalContext(requestId: string): Promise<void> {
     try {
       const output = await getTerminalContents(-1)

packages/kilo-vscode/src/kilo-provider/message-files.ts

@@ -12,7 +12,8 @@ const source = z.object({
 
 const file = z.object({
   mime: z.string(),
-  url: z.string().refine((url) => url.startsWith("file://") || url.startsWith("data:")),
+  // session: URLs reference a past chat; the backend resolves them into transcript context
+  url: z.string().refine((url) => url.startsWith("file://") || url.startsWith("data:") || url.startsWith("session:")),
   filename: z.string().optional(),
   source: source.optional(),
 })

packages/kilo-vscode/src/kilo-provider/session-search.ts

@@ -0,0 +1,51 @@
+import type { KiloClient } from "@kilocode/sdk/v2/client"
+
+type Item = {
+  id: string
+  title: string
+  updated: number
+}
+
+type Message = {
+  requestId: string
+  sessionID?: string
+}
+
+type Input = {
+  client: KiloClient | null
+  message: Message
+  current?: string
+  context?: string
+  dir: (id?: string) => string
+  exclude?: string
+  post: (message: unknown) => void
+}
+
+/**
+ * Past-chat mention search. Lists root sessions for the directory the current
+ * chat runs in (workspace root for the sidebar, the worktree for Agent Manager
+ * sessions) — the same directory-scoped `session.list` the session history and
+ * Agent Manager search are built on. Fuzzy title filtering happens in the
+ * webview (same mechanism as the Agent Manager sidebar search).
+ */
+export async function handleSessionSearch(input: Input): Promise<void> {
+  const client = input.client
+  if (!client) {
+    input.post({ type: "sessionSearchResult", sessions: [], requestId: input.message.requestId })
+    return
+  }
+
+  const id = input.message.sessionID ?? input.current ?? input.context
+  const dir = input.dir(id)
+
+  try {
+    const res = await client.session.list({ directory: dir, roots: true, limit: 50 }, { throwOnError: true })
+    const sessions: Item[] = res.data
+      .filter((session) => session.id !== input.exclude && session.title)
+      .map((session) => ({ id: session.id, title: session.title, updated: session.time.updated }))
+    input.post({ type: "sessionSearchResult", sessions, requestId: input.message.requestId })
+  } catch (err) {
+    console.error("[Kilo New] Session search failed:", err)
+    input.post({ type: "sessionSearchResult", sessions: [], requestId: input.message.requestId })
+  }
+}

packages/kilo-vscode/tests/unit/file-mention-utils.test.ts

@@ -5,11 +5,18 @@ import {
   buildTextAfterMentionSelect,
   buildFileAttachments,
   buildMentionResults,
+  buildSessionAttachments,
   filterMentionResults,
   getMentionRemovalRange,
+  getPastChatsMentionResult,
   isCursorAtMentionEnd,
   findMentionRange,
+  sessionMentionFilename,
+  sessionMentionText,
+  sessionMentionToken,
+  syncMentionedSessions,
   FILE_PICKER_RESULT,
+  PAST_CHATS_RESULT,
   TERMINAL_RESULT,
   GIT_CHANGES_RESULT,
 } from "../../webview-ui/src/hooks/file-mention-utils"
@@ -89,6 +96,7 @@ describe("buildMentionResults", () => {
     expect(result).toEqual([
       TERMINAL_RESULT,
       GIT_CHANGES_RESULT,
+      PAST_CHATS_RESULT,
       { type: "file", value: "src/index.ts" },
       FILE_PICKER_RESULT,
     ])
@@ -552,3 +560,111 @@ describe("findMentionRange", () => {
     expect(findMentionRange(text, 4, paths)).toEqual({ start: 3, end: 6 })
   })
 })
+
+describe("session mentions", () => {
+  const now = Date.now()
+  const sessions = [
+    { id: "ses_a", title: "Fix auth bug", updated: now },
+    { id: "ses_b", title: "Rotate signing keys", updated: now - 1000 },
+    { id: "ses_c", title: "Refactor cache layer", updated: now - 2000 },
+  ]
+
+  describe("getPastChatsMentionResult", () => {
+    it("offers the past-chats picker for an empty query", () => {
+      expect(getPastChatsMentionResult("")).toEqual([PAST_CHATS_RESULT])
+    })
+
+    it("offers the picker for alias prefixes", () => {
+      expect(getPastChatsMentionResult("pas")).toEqual([PAST_CHATS_RESULT])
+      expect(getPastChatsMentionResult("sess")).toEqual([PAST_CHATS_RESULT])
+      expect(getPastChatsMentionResult("hist")).toEqual([PAST_CHATS_RESULT])
+    })
+
+    it("hides the picker for unrelated queries", () => {
+      expect(getPastChatsMentionResult("index")).toEqual([])
+    })
+  })
+
+  describe("sessionMentionText / filename", () => {
+    it("collapses whitespace in titles", () => {
+      expect(sessionMentionText("Fix\nauth   bug")).toBe("Fix auth bug")
+    })
+
+    it("slugifies titles for the attachment filename", () => {
+      expect(sessionMentionFilename("Fix auth bug", "ses_a")).toBe("Fix-auth-bug.md")
+    })
+
+    it("falls back to the session id when the slug is empty", () => {
+      expect(sessionMentionFilename("???", "ses_a")).toBe("ses_a.md")
+    })
+
+    it("disambiguates sessions with the same title", () => {
+      const known = new Map([["Fix auth bug", sessions[0]!]])
+      expect(sessionMentionToken({ ...sessions[1]!, title: "Fix auth bug" }, known)).toBe("Fix auth bug (2)")
+    })
+
+    it("reuses the token already assigned to a session", () => {
+      const known = new Map([["Fix auth bug (2)", sessions[1]!]])
+      expect(sessionMentionToken(sessions[1]!, known)).toBe("Fix auth bug (2)")
+    })
+  })
+
+  describe("buildMentionResults", () => {
+    it("offers the past-chats picker alongside the other special mentions", () => {
+      const result = buildMentionResults("", [])
+      expect(result[0]).toEqual(TERMINAL_RESULT)
+      expect(result).toContainEqual(PAST_CHATS_RESULT)
+      expect(result[result.length - 1]).toEqual(FILE_PICKER_RESULT)
+    })
+  })
+
+  describe("filterMentionResults", () => {
+    it("keeps the past-chats picker for alias queries", () => {
+      const filtered = filterMentionResults("sess", buildMentionResults("", []))
+      expect(filtered).toContainEqual(PAST_CHATS_RESULT)
+    })
+  })
+
+  describe("syncMentionedSessions", () => {
+    it("drops sessions whose token is no longer present in the text", () => {
+      const prev = new Map([
+        ["Fix auth bug", sessions[0]!],
+        ["Rotate signing keys", sessions[1]!],
+      ])
+      const kept = syncMentionedSessions(prev, "see @Fix auth bug here")
+      expect(kept.has("Fix auth bug")).toBe(true)
+      expect(kept.has("Rotate signing keys")).toBe(false)
+    })
+  })
+
+  describe("buildSessionAttachments", () => {
+    it("builds a session: attachment with span offsets and a readable filename", () => {
+      const mentioned = new Map([["Fix auth bug", sessions[0]!]])
+      const attachments = buildSessionAttachments("check @Fix auth bug out", mentioned)
+      expect(attachments).toHaveLength(1)
+      const att = attachments[0]!
+      expect(att.mime).toBe("text/plain")
+      expect(att.url).toBe("session:ses_a")
+      expect(att.filename).toBe("Fix-auth-bug.md")
+      expect(att.source?.type).toBe("file")
+      expect(att.source?.text.value).toBe("@Fix auth bug")
+      expect(att.source?.text.start).toBe(6)
+      expect(att.source?.text.end).toBe(19)
+    })
+
+    it("skips sessions whose token is not present in the text", () => {
+      const mentioned = new Map([["Fix auth bug", sessions[0]!]])
+      expect(buildSessionAttachments("nothing here", mentioned)).toEqual([])
+    })
+
+    it("attaches distinct sessions whose titles collide", () => {
+      const mentioned = new Map([
+        ["Fix auth bug", sessions[0]!],
+        ["Fix auth bug (2)", { ...sessions[1]!, title: "Fix auth bug" }],
+      ])
+      const attachments = buildSessionAttachments("compare @Fix auth bug with @Fix auth bug (2)", mentioned)
+      expect(attachments.map((item) => item.url)).toEqual(["session:ses_a", "session:ses_b"])
+      expect(attachments.map((item) => item.source?.text.value)).toEqual(["@Fix auth bug", "@Fix auth bug (2)"])
+    })
+  })
+})

packages/kilo-vscode/tests/unit/message-files.test.ts

@@ -23,4 +23,22 @@ describe("parseMessageFiles", () => {
   it("rejects unsupported URLs", () => {
     expect(parseMessageFiles([{ mime: "text/plain", url: "https://example.com/file.txt" }])).toBeUndefined()
   })
+
+  it("accepts past-chat session attachments", () => {
+    const files = parseMessageFiles([
+      {
+        mime: "text/plain",
+        url: "session:ses_07c08a2ddffeXample",
+        filename: "fix-auth-bug.md",
+        source: {
+          type: "file",
+          path: "session:ses_07c08a2ddffeXample",
+          text: { value: "@Fix auth bug", start: 0, end: 13 },
+        },
+      },
+    ])
+
+    expect(files?.[0]?.url).toBe("session:ses_07c08a2ddffeXample")
+    expect(files?.[0]?.filename).toBe("fix-auth-bug.md")
+  })
 })

packages/kilo-vscode/webview-ui/src/App.tsx

@@ -202,6 +202,7 @@ export const DataBridge: Component<{ children: any }> = (props) => {
       onOpenUrl={openUrl}
       onOpenContent={openContent}
       onValidateFiles={validateFiles}
+      onNavigateToSession={(id) => session.selectSession(id)}
     >
       {props.children}
     </DataProvider>